Magnetic Monopoles

[insane_alien]

for a point charge yes. for multiple point charges in a line then this relationship is no longer valid although can be derived using the Biot-Savart law until you eventually get a 1/r relationship with an infinitely long wire. wires also start behaving like an infinitely long wire pretty quickly. anything longer than a few meters can be taken to be following a 1/r rule.

[swansont]

As explained in Wikipedia article these equations are for moving charges and currents. Since the magnitude depends on velocity there would not be any magnetic field if these charges were not moving.

 

It's even called "magnetic field of MOVING charge".

 

Yes, exactly. And we are discussing whether something is a monopole, in the context of Maxwell's equations. If you require the 1/r^2 behavior, then we are discussing the fields when the particles are at rest. Under these conditions, there are no magnetic monopoles.

 

All the rest is playing at semantic games.

 

Now, is there anything new to discuss? If we're just going to revisit the same ground, then there's no reason for the thread to remain open.

[Mr Skeptic]

Ok, I used car battery this time and I confirmed only one pole.

 

When you report on your experiment, you are supposed to use enough detail that someone else can set up exactly the same experiment as you. As it is, we have no idea what you did nor how you came to your conclusions, so as far as anyone other than you is concerned, you might as well not have done any experiment. What exactly did you do? How did what you do confirm only one pole? Is it a north or a south pole? You need to describe separately the set up (enough that someone else can repeat it), the results, your conclusions, and how you came to the conclusions.

[Sha31]

for a point charge yes (1/r^2).

 

Thank you.

 

---

Merged post follows:

Consecutive posts merged

If you require the 1/r^2 behavior' date=' then we are discussing the fields when the particles are at rest.

[/quote']

 

No. Again, these equations are for moving charges.

 

Magnetic field due to moving charges and electrical currents

 

http://en.wikipedia.org/wiki/Magnetic_field#Magnetic_field_due_to_moving_charges_and_electrical_currents

 

 

Look, Biot-Savart equation for point charges has "v" for 'charge velocity':

 

http://en.wikipedia.org/wiki/Biot-savart

 

 

Now' date=' is there anything new to discuss? If we're just going to revisit the same ground, then there's no reason for the thread to remain open.

[/quote']

 

Huh? How do you know other people would not like to talk about this? This is not some kind of taboo, is it? This is a public forum, right? -- I've proven my point in so many ways, the real question is what part are you still trying to deny and with what arguments?

 

 

 

You did not answer this question:

 

Usually, 'pole' is defined as the point where the field magnitude is strongest. So, how would you define "pole" and how many poles do you think magnetic field of moving charge has? None, one, two, many?

 

---

Merged post follows:

Consecutive posts merged

When you report on your experiment, you are supposed to use enough detail that someone else can set up exactly the same experiment as you. As it is, we have no idea what you did nor how you came to your conclusions, so as far as anyone other than you is concerned, you might as well not have done any experiment. What exactly did you do? How did what you do confirm only one pole? Is it a north or a south pole? You need to describe separately the set up (enough that someone else can repeat it), the results, your conclusions, and how you came to the conclusions.

 

I define pole as the strongest point of a field. I found magnetic strength diverges toward only one point, where polarity is dependent of the electron velocity vector i.e. current direction. Therefore, I concluded magnetic field of a moving charge(s) is monopole.

 

 

My turn.

 

a.) Magnetic filed of a single moving charge drops off as 1/r^2, yes?

 

b.) How do you define filed 'pole'?

 

c.) How do you explain magnetic field of moving charge has "no poles"?

 

d.) Can you provide some reference for the claims you're going to make?

Edited December 4, 2009 by Sha31
Consecutive posts merged.

[Mr Skeptic]

I define pole as the strongest point of a field. I found magnetic strength diverges toward only one point, where polarity is dependent of the electron velocity vector i.e. current direction. Therefore, I concluded magnetic field of a moving charge(s) is monopole.

 

So did you do an experiment or not? All we know is that you played with magnets and wires and don't know what you are talking about. You didn't answer any of the questions about your experiment -- especially set up and results. In fact from the sounds of it you got your conclusions without doing any experiment. If you did an experiment why leave out the most important parts and give us entirely useless information about it instead?

 

My turn.

 

a.) Magnetic filed of a single moving charge drops off as 1/r^2, yes?

 

Your turn?!? When you make a claim it is up to you and only you to support it. However, I will respond anyways if it helps you. Incidentally, the questions we ask are intended to help you learn, or to help us understand what you are saying.

 

Yes, but unlike a monopole this field is perpendicular to the line connecting the particle to that point, and the particle does not act as a source for that field, just makes circular field lines.

 

b.) How do you define filed 'pole'?

 

A monopole is either a source or a sink of a field (or field lines). The "pole" of a diopole is the part of it that looks kind of like a monopole on one side, ie the field lines are either entering or leaving though only on one side of it. I would agree that if poles exist they should be the two points where the field is strongest, as for all the field lines to enter or leave a point they have to be very close together indicating a very strong field.

 

c.) How do you explain magnetic field of moving charge has "no poles"?

 

It's a magnetic field. Why should it have any poles? If you want to say it has poles or only one pole, what evidence do you have? And again, is it a north or south pole?

 

d.) Can you provide some reference for the claims you're going to make?

 

Yes, unlike you.

[Sha31]

So did you do an experiment or not? All we know is that you played with magnets and wires and don't know what you are talking about. You didn't answer any of the questions about your experiment -- especially set up and results. In fact from the sounds of it you got your conclusions without doing any experiment. If you did an experiment why leave out the most important parts and give us entirely useless information about it instead?

 

Ok' date=' maybe I got it wrong, but that's why you're here, so please tell us:

 

- Does magnetic field of a current carrying wire attract or repel north pole or south pole of a permanent magnet, both or neither?

 

 

Yes, but unlike a monopole this field is perpendicular to the line connecting the particle to that point, and the particle does not act as a source for that field, just makes circular field lines.

 

But force is perpendicular to that field so the force vector actually does point toward the charge, hence two parallel current carrying wires attract.

 

REFERENCE:

http://en.wikipedia.org/wiki/Lorentz_force

http://en.wikipedia.org/wiki/Amp%C3%A8re%27s_force_law

http://en.wikipedia.org/wiki/Z-pinch

"The Z-pinch is an application of the Lorentz force, in which a current-carrying conductor in a magnetic field experiences a force. One example of the Lorentz force is that, if two parallel wires are carrying current in the same direction, the wires will be pulled toward each other. The Z-pinch uses this effect: the entire plasma can be thought of as many current-carrying wires, all carrying current in the same direction, and they are all pulled toward each other by the Lorentz force, thus the plasma contracts."

 

 

 

A monopole is either a source or a sink of a field (or field lines). The "pole" of a diopole is the part of it that looks kind of like a monopole on one side' date=' ie the field lines are either entering or leaving though only on one side of it. I would agree that [i']if poles exist[/i] they should be the two points where the field is strongest, as for all the field lines to enter or leave a point they have to be very close together indicating a very strong field.

 

No, that's maybe valid for electric monopoles, but that is not the definition of what "pole" is. Can you provide some reference to support what you said?

 

 

Pole is defined as the origin of some field, the point where the field is strongest and from where it's magnitude drops with 1/r^2 if it is monopole. Field lines are not part of the definition of what 'pole' is, they only describe topology or direction of the field.

 

 

It's a magnetic field. Why should it have any poles?

 

Can you provide some reference to support the claim how magnetic, or any other fields, can exist without poles?

 

 

By the way, fields "need" poles as to define where the field magnitude is strongest and where from the magnitude will drop off, so to put some coordinates into those equations and calculate vectors and trajectories. How exactly do you calculate distance vector "r" in Biot-Savart law and Lorentz force equations, how do you model forces in coordinate system if you don't know where are, and how many, magnetic poles you have? Without poles (field origins) those equations would simply not work, but they do work exactly as equations for monopoles should.

Edited December 4, 2009 by Sha31

[uncool]

Sha31: Consider the magnetic field

[MATH]\overline{B} = x \hat{j}[/MATH].

 

This is a normal field. A pole is any place where the divergence of the field is nonzero. Where is that here?

 

If we consider the wire, we still get that the divergence of the field is 0 - and therefore, that there are no poles.

 

There are plenty of fields with zero divergence. Consider any vector function on [MATH]\mathbb{R}^3[/MATH] A. Then if we let B be the curl of A, that is a divergenceless field. A is known as the vector potential. Then B has no poles.

=Uncool-

[Mr Skeptic]

Ok, maybe I got it wrong, but that's why you're here, so please tell us:

 

- Does magnetic field of a current carrying wire attract or repel north pole or south pole of a permanent magnet, both or neither?

 

Shall I take that to mean that you lied about doing the experiment? If you did this experiment, how come you need to know the result of it? And why do you insist on not describing your experimental set up and results?

 

But force is perpendicular to that field so the force vector actually does point toward the charge, hence two parallel current carrying wires attract.

 

REFERENCE:

http://en.wikipedia.org/wiki/Lorentz_force

http://en.wikipedia.org/wiki/Amp%C3%A8re%27s_force_law

http://en.wikipedia.org/wiki/Z-pinch

"The Z-pinch is an application of the Lorentz force, in which a current-carrying conductor in a magnetic field experiences a force. One example of the Lorentz force is that, if two parallel wires are carrying current in the same direction, the wires will be pulled toward each other. The Z-pinch uses this effect: the entire plasma can be thought of as many current-carrying wires, all carrying current in the same direction, and they are all pulled toward each other by the Lorentz force, thus the plasma contracts."

 

Of course. Everyone knows that electric charges moving through a magnetic field experience a force perpendicular to both their motion and the magnetic field. Your example shows what I told you, that the magnetic field is perpendicular to the charges.

 

No, that's maybe valid for electric monopoles, but that is not the definition of what "pole" is. Can you provide some reference to support what you said?

 

Yes, the first two of Maxwell's Equations.

 

Pole is defined as the origin of some field, the point where the field is strongest and from where it's magnitude drops with 1/r^2 if it is monopole. Field lines are not part of the definition of what 'pole' is, they only describe topology or direction of the field.

 

That's what I said, in different words. The origin of the field necessarily means the origin of the field lines, because of what field lines represent.

 

And this disproves your claim, as the magnetic field of a current carrying wire or of a moving charge never acts as a source for a magnetic field.

 

Can you provide some reference to support the claim how magnetic, or any other fields, can exist without poles?

 

I already proved that by example -- the magnetic field of a moving charge.

 

You are claiming that a magnetic field requires poles, and I disproved you. Care to provide show my example invalid or provide a reference for your claim? Note that you were the first to make a claim about this, and rather than ask you for a source I saved you the trouble by disproving you. But now it seems I need to ask you for a source, so that you believe me since you can't find one.

 

By the way, fields "need" poles as to define where the field magnitude is strongest and where from the magnitude will drop off, so to put some coordinates into those equations and calculate vectors and trajectories. How exactly do you calculate distance vector "r" in Biot-Savart law and Lorentz force equations, how do you model forces in coordinate system if you don't know where are, and how many, magnetic poles you have? Without poles (field origins) those equations would simply not work, but they do work exactly as equations for monopoles should.

 

Why should a vector field need a strongest point?

[Sha31]

A pole is any place where the divergence of the field is nonzero.

 

Where did you get that definition from?

 

- Pole is the place where the field magnitude is strongest. This is the definition used in all the equations. Is there something wrong with this definition' date=' can we agree?

 

 

The field magnitude is determined by force, and the direction of the force can be different to the direction of the field. How many places does magnetic field of moving charge have where this magnetic force is strongest?

 

Filed lines or topology has nothing to do with number of poles or what pole actually is. Consider a solid box with cone shape cut out on the top pointing down the bottom. It's a kind of sink and its topological lines would be in the direction of attraction. But, consider this box is liquid or gas and instead of rigid sink you have a whirlpool or tornado. Topology of this "field" would show concentric circular direction, but the force would still act directly inwards, right? -- So, we obviously need to distinguish between field lines and force lines. Force lines always point towards a pole, but filed lines do not need to. Do you agree?

[mp']Consecutive posts merged[/mp]

And this disproves your claim' date=' as the magnetic field of a current carrying wire or of a moving charge never acts as a source for a magnetic field.

[/quote']

 

What then is the source of magnetic field of moving charge if not the charge itself?

 

 

 

Can you provide some reference to support the claim how magnetic' date=' or any other fields, can exist without poles? [/b']

 

I already proved that by example -- the magnetic field of a moving charge.

 

What kind of reference is that? No one sane, in the whole world, will ever agree with you, nor has anyone ever said anything like that, anywhere, ever. So, you should really try to find some reference as to finally wake up from your hallucination.

 

But, you do agree "pole" is defined with the point where field is strongest, then why is not this moving charge a 'pole' since that's where its magnetic field is strongest?

 

 

Why should a vector field need a strongest point?

 

Vectors need initial position, direction and magnitude.

 

How else do you imagine we can use Biot-Savart law without knowing where the fields are? How do you calculate distance and magnitude of magnetic field of moving charge? Where from does magnitude in "your equations" start to drop off?

 

It looks like a duck, walks like a duck, quacks like a duck... and you call it owl.

Edited December 4, 2009 by Sha31
Consecutive posts merged.

[uncool]

Where did you get that definition from?

I got it from my electrodynamics classes, and from reading on this exact subject. Look up Gauss's law for magnetism.

 

- Pole is the place where the field magnitude is strongest. This is the definition used in all the equations. Is there something wrong with this definition, can we agree?

Do you mind showing me where it is used as such in any equations? I can positively say that I have never seen such a definition.

 

You'll notice that Maxwell's equations for magnetism say specifically that the magnetic field has no divergence. That is the exact statement that magnetic monopoles do not exist.

=Uncool-

[insane_alien]

ah so thats your plan sha31, just use different meanings from everyone else to try an make you look smart?

 

i've got nes for you, it makes you looks like an immature child. if i decided to reffer to all chairs as magnetic monopoles does that mean what scientists reffer to as magnetic monopoles exist? no. it makes me look like a complete fool and nothing more.

 

grow up, go learn some of the actual science and math behind this and then maybe have an adult conversation where you don't just go 'im right you're wrong lalalala'

[swansont]

No. Again, these equations are for moving charges.

 

And, once again, what physicists mean by "monopole" is different from what you are insisting upon. Specifically, you get the 1/r^2 behavior in the particle's rest frame when you solve Maxwell's equations. In a moving frame, you get something else. So if you want to use that as a criterion, you have to meet the conditions under which it applies.

 

 

Huh? How do you know other people would not like to talk about this? This is not some kind of taboo, is it? This is a public forum, right? -- I've proven my point in so many ways, the real question is what part are you still trying to deny and with what arguments?

 

We aren't covering any new ground, and everyone in the discussion who know some physics are telling you you're wrong and that you are reaching your conclusion by changing the definitions that physicists use (IOW, the only one who thinks you've proved your point is you). You've had an opportunity to learn some physics here, but whether you take advantage of that is up to you.

 

 

As far as this being a public forum, it depends on what you mean by "public." It is accessible to most, as long as they can access the web. But there are rules to follow, and the purpose is to discuss science — it is not a free-for-all. It is not "public" in the sense that you have a right to post anything you wish. Merely repeating a point is soapboxing (or worse, trolling), and against the rules.

 

This thread is now closed.